Umbra on chlorine

So I’ve been buying unbleached diapers for my baby, using chlorine-free laundry and dish soaps and non-chlorine bleached paper, and generally thinking that’s better for me and the environment. Then I go swimming in a chlorinated pool twice a week, sometimes with my kids! Is there a difference in the type of chlorine exposure? Is swimming a health risk? It certainly bothers my nose (I think I’ll start using some nose plugs). Can you explain some more of the science behind the effects of chlorine?

Joan Haysom Ottawa, Ontario, Canada

Dearest Joan,

Quite a dilemma, you’re right. But take strength in numbers, because you are far, far from alone in this conundrum — I’m with you. At least we’re together. And your instincts are correct: The major issues with bleached paper products and chlorinated dish soap are different from the major issues with chlorinated pools.

Dioxins are a category of chemical, a sort of evil family that is a byproduct of the manufacturing and disposal of chlorine. They are highly persistent in the environment and harmful to our health as well as the health of other living beings. Pretty much everyone agrees that dioxins are carcinogens and disruptive to our hormonal and reproductive systems. The point of purchasing unbleached paper and avoiding vinyl (that’s final!), etc., isn’t to protect us from immediate dioxin exposure in our homes, but to protect the larger environment from further dioxin buildup.

We primarily take up dioxins not from our paper products but through our food, because they accumulate in the food chain, in fatty tissues. Vegans have got it right on that count and many others: to eat less dioxin, eat no meat or dairy products. Sadly, this applies to human breast milk as well. (Breast milk is still the best food for babies, but feel free to stop drinking cow and yak milk.)

Your shopping (or lack thereof — not shopping at all is often ecologically fabulous) is helping the larger environment and eventually filtering down to help you a little, or maybe your great-grandchildren. Swimming, on the other hand, is all about your immediate environment and how it will affect your health.

I wrote about pools a few years back, and other articles in Grist have covered the slow reveal on health problems resulting from pool chlorine. The chlorine is used to keep us safe from very unpleasant bacteria such as cryptosporidium and E. coli, but it reacts with air and human bodies to make a wide variety of new chemical compounds. Swimmers, who are breathing rapidly either because they are exercising or because they are children, or both, then inhale and absorb and swallow these compounds. Basically, the news is sobering, and after I wrote the pool piece we got a nice letter from an academic adding that the trihalomethanes I had highlighted as bad news were only a few of the phalanx of dangerous chemicals created when chlorine reacts with organic substances (dioxin is one of these items). Then last year Belgians linked chlorinated pool exposure to asthmatic wheezing.

Back to your original question. I hope I have clarified the difference in chlorine exposure: one is big picture and the other is immediate; but both have to do with chemicals created when chlorine interacts with organic compounds. Swimming pools are a health “risk,” yes, but a “risk” in the sense that it may be a problem or it may not — we don’t quite know. I don’t think pool water is yet called a health hazard. I’m not giving you too much detailed chlorine science; if you want organic chemistry, you’ll have to ask elsewhere. Should you swim with your kids at the pool? I can’t make that choice for you. Maybe you could have a discussion with pool staff about the levels of chlorine (they are regulated by health codes so won’t vary much), the adequacy of ventilation, and their own awareness of chlorine overexposure, and that discussion could help you decide.